Motor-control system



Dec} 16; 1924.

J. R. WILSON NO' 10R CONTROL SYSTEM Filed Dec. 31 1921 2 Sheets-Sheet 1 INVENTOR James/1. Wllsafl.

-44 T E ia. 25%

WITNE ATTORNEY J. R. WILSON MOTOR CONTROL SYSTEM Filed Dec. 31 1921 2 Sheets-Sheet 2 L m F WITN ESSES:

ATTORNEY Patented Dec. 16, 1924.

UNlTED STATES PATENT OFFICE.

JAMES 3. WILSON, 0F WILKINSBURG, PENNSYLVANIA, ASSIGNOR TO WESTINGHOU SE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF IPENNSYLVANIA.

MOTOR-CONTROL sYs'TEM.

Application filed December 31, 1921. Serial No. 526,157.

To all whom it may concern:

. Be it known that I, JAMES R. VVILsoN, a citizen of the United States, and a resident of Wilkinsburg, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Motor- Control Systems, of which the following is a specification.

My invention relates to motor-control'systems and it has particular relation to motorcontrol systems employing a phase-converter to translate-single-phase energy into threephase energy.

The object of my invention is to provide an improved method of starting a phaseconverter that is employed to translate one form of electrical energy into another form.

Heretofore, such apparatus as has been constructed for starting a phase-converter has proved somewhat unsatisfactoryby reason of a heavy surge of current traversing the primary winding of the phase-converter when the rimary winding is first connected across sulistantially the entire secondary windin of the main supply transformer. .Brie y speaking, my invention consists in employing the groups of switches that govern the phase-balancing functions of the primary and tertiar windings of a phase-converter to also e ect a gradual increase in the ener ization of the phase-converter.

, For a lietter understanding of my invention, reference may be made to the accompanying drawings,

Figure 1 of which is a schematic view of the main circuits of a motor-control system employing a phase-converter and organized in accordance with my invention;

Fig. 2 is a sequence chart showing the order of closure of a plurality of switches illustrated in Fig. 1 of the drawings;

Fig. 3 is a diagrammatic View of the auxiliary circuits that are employed to govern the switches which are illustrated in Fig. 1 of the drawings; and

Fig. 4 is a diagrammatic view of one of the switches illustrated in Fig. 1 of the drawings.

Referring particularly to Fig. '1 of the drawings, a plurality of switches l to 15, inclusive, are employed to govern the energization of a phaseconverter 16, having a primary winding 17, a tertiary winding 18 and a squirrel-cage rotor 19 also having a direct--current exciting winding. 19a. .The phase-converter 16 is employed totranslate single-phase energy, supplied froma trolley conductor 21 and return. circuit marked Ground, to three-phase energy for operating a plurality of induction motors 22 and 23. The motors 22 and 23 are each provided with a primary winding 2% and a secondary winding 25. A plurality of liquid rheostats 26, which may be constructed in accordance with any usual practice, are:employed for governing the resistance in circuit.wit hthe secondary winding 25 of each of the motors 22 and 23.

The switches l to 15, inclusive, are lconnected to a plurality of taps of a secondary winding 27 of a main supply tra ns former 28. The main. transformer 28 is provided with a primary winding29, which is energized, upon .the closure of a circuitbreaker 31, through a circuit that is established from the trolley conductor 21 through pantograph 32, circuit-breaker .31 and primary winding 29 of main transformer 28 to ground. An auxiliary dynamo-electric machine or motor 33, mechanically connected to the phasecon\erter 16 by means of a shaft 34, is employed initially to act as a motor to start the phase-converter 16 and to function as a generator to energize the rotor winding 19a. v

The auxiliary motor 33 is provided with an armature 35, a main series field-magnet winding 36, an auxiliary or commutating field-magnet winding 37 and a divided fieldmagnet winding 38. The divided field-magnet winding 38 of the auxiliary motor 33 may be energized by a motor-generator set 39, comprising an armature 41 and a fieldmagnet winding 42.

A changeover switch 43, having a start and a run position, is employed for connecting the armature 1l of the motor-generator set 39 to the divided field-magnet winding 38 of the auxiliary motor 33 and for connecting the armature 35 of the auxiliary motor 33 to the rotor winding 19a of the phase-converter 16, upon the phase-converter 16 attaining substantially synchronous speed.

The primary winding 21 of each of the main driving motors 22 and 23 may be connected to theseoondary winding 27 of the transformer 28 and the tertiary winding 18 of the phase-converter 16 by means of a plurality of circuit-breakers or line switches 44 and a plurality of conductors 44a, 44b, and 440 in' accordance with standard practice.

The operation of the switches l to 15, inclusive,.is governed during the starting of the phase-converter 16, by a sequence drum 45 (see Fig. 3), a starting motor relay 46, a. phase-converter relay 47 a, and a cunrent relay 48a, in a manner-hereinafter more fully described.

' The-sequence drum 45*is provided with anfotf position and a plurality of operating; positions a to z inclusive. The sequence drum 45 may be actuated by means of a PK engine 46 ,"comprising a shaft 47, which is' secured the rotatable drum 45, apinion: 48, which is secured to'the endof the shaft 47and actuatedjby arack-membef"49,= and a, pair of pistons 51 and 52, which are mounted at-opposite ends of the rajcikmember 49 and travelw'ithinthe cylinders=53and 54, respectively. I

Movement ofthe rotatable shaft 47 to bring the drum into the illustrated ofi position is effected by applying air pressure to the piston 52, which is governed by an electromagnetic valve device 55. The sequence drum '45 is actuated through its upcrating positions when pressure is applied to the piston 51 and concurrently released from the piston 52. Air is supplied to the cylinder 53 through an electromagnetic valve device or on valve 56, which comprises. a valve stem 57, having outlet and inlet valve members 58 an'd 59, respectively, mounted thereon. The valve stem 57 is actuated by an armature member 61, upon the energization of a coil 62, to elfect the closure of the outlet valve 58 and the opening ofthe normally closed inlet valve 59 to apply pressure to the piston 51. When the coil 62 is de-energized, a resilient member 63 actuates the valve stem 57 to effect the closure of the inlet port 59 and the opening of the outlet port 58.

The electromagnetic valve device or off valve 55 comprises a normally open inlet valve 65 and a normally closed outlet valve 66, which are mounted upon a-valve stem 67. An armature member 68 is secured to one end of the valve stem 67 andserves to actuate it to effect closure of the inlet valve 65 and the opening of the outlet valve 66 upon the energization of an actuating coil 69. A resilient member 70 maintains the inlet valve 65 normally opened and the outlet valve 66 normally closed.

Vhen the coils 62 and 69 are concurrently tie-energized. the PK engine 46 returns the drum 45 to its off position. When both coils are concurrently energized, the PK engine 46 actuates the drum 45 to one of its operating positions. When the coil 62 is energized, and the coil 69 is de-energized, air pressure is simultaneously applied to both the pistons 51 and 52 to maintain the rack member 49 in Whatever position it may, at the time, occupy.

Referring toFig. 4 of the drawings, the switchlO is provided with an actuating coil for actuating the main contact member 10 from its open to its closed position, to open a plurality of auxiliary contact members or interlocks "10-out* and to close a plurality of auxiliary contact members or interlocks lO-in. all of tht auxiliary contact members being mechanically connected to the main contact member 10. The auxiliary contact devices of the switch 10 will be referredto as interlocks, the operation thereof being well understood by those'skilled in the art.

The remaining switches 1 to 9 and 11 to 13, inclusive, are constructed in substantially the same manner as switch 10, with the exception of the interlocks. Switches 14 and 15 are also provided with interlocks, which are arranged in accordance with the requirements of the portion of the control system in which they are employed.

The actuating coils of the switches 1 to 7, inclusive, 10, and 13 to 15, inclusive, are illustrated in Fig. 3 of the drawings. After switch 10 has assumed its closed position, these coils may be energized through a controller 71 to operate the corresponding switches, thereby varying the energization of the primary winding 17 and tertiary winding 18 of the phase'converter 16 to effeet phase-balancing of the three-phase primary winding 24 oi each of the motors 22 and 23.

The purpose and method of securing phase-balancing are well understood to those skilled in the art of railway-motorcontrol systems and is fully described in a number of patents, for instance, No. 1,243,430, to B. G. Lemme, dated Oct. 16, 1917, and assigned to the WVestinghouse Electric and Manufacturing Company.

Briefly speaking, phase-balancing is effected by shifting one of the terminals of the primary winding 17 ot' the phase-converter 16 across the secondary winding 27 of the main transformer 28 by means of the switches 8 to 12, inclusive. and by shifting the connection of the tertiary winding 18 of the phase-converter 16 along the central portion of the secondary winding 27 of the main transforn'ier 28, by means of the switches 1 to 7, inclusive, to balance the two phases that may be represented by the pairs of conductors 44a and 44b and 44a and 440 with the third phase represented by conductors 447) and 440.

Heretofore. in starting a phase-converter, the primary winding 17 of the phase-converter 16 has been first connected, by means of a switch,to"a tap corresponding to switch 1 and, after the phase-converter 16 has attained substantially synchronous speed, the terminahof the primary winding 17 of the phase-converter 16 was-disconnected from this tap and connected'to' a tap corresponding to switclr'lO. This sudden change in the connection of'the primary winding 17 caused a heavy surge of current through it a nd was very undesiralblebecause of the shockto the phase-converter-l6- and' the control system in which the phase converter'was employed, upon the occurrence of this transition. The shocks to the' phase-converter have been so great as to caus'e appreciable vibration of the locomotive upon -.which the phase-converter was mounted. 7 3 By imeans "of switch 15, the primary winding'17 of'the-phase-converter 16 is con nected to the-group of' switchesl to 7, inclusive, and 13, thereby permitting a gradual step-by-stepsvaria'tion in voltage of the primary winding =17 by the closure of the Switches 1 to7, inclusive, during the period that .the phase-conve rter 16 is brought to synchronous speed and'voltage is being built up in it. During the starting of:the phaseconverter- 16, the'operation of the switches 1 to 7, inclusive, 10, 13 and 15.is governed by the sequence drum 45.

Whemcontactor l0-'s closed, the coils 62 and 690i thezivPK engine 46 are de-energized and .-thes sequence drum is returned toits off position, thereby connecting the switches 1 to7-, -inclusive, 13 and to controller 71 through interlocks which are mounted upon thedrum 45. :The controller 71 is employed to govern these. switches to effect phase-balancing, as has been previously described.

The full operation of the control system, as illustrated, is as follows: A hand switch 72 (see Fig. 3 of the drawings) is first closed to effect energization of the actuating coil of the switch 14 by a battery 73 or other suitable source of electrical energy. Upon the'ener ization of the actuatingxcoil of the switc 14, the switch assumes its closed position, thereby establishing a circuit from the end tap of the secondary winding 27 of the main transformer 28 through the primary winding 74 of a current transformer 75, which governs the energization of the current relay 48, primary winding 17 of the phase-converter 16, a portion of preventive coil 76, switch 14, series field-magnet winding 36, armature and auxiliary field-magnet winding 37 of the auxiliary motor 33, and control fingers 77 and 77a, which are bridged by contact segment 78 of the changeover switch 43, to the tap of the secondary winding 27 of the main transformer 28, to which the switch 10 is connected. When the auxiliary motor 33 attains a predetermined speed, the starting motor relay 46a, which is governedby the counter-electromoti've force of the auxiliary motor 33, assumes its closed position.

When the starting motor relay 46a is closed, the actuating coil of the switch 15 is energized by a circuit from the battery 73 through a'manually-operated switch 72, contact member of the starting motor relay 46a, interlock 14-in, control fingers 79"and 81, which are-bridged by contact segment 82 of the sequence'drum and actuating coil of the switch 15 to the negative terminal of the battery 73. Theactuating coil of the switch 1 is connected in'parallel relation to the switch 15 through control fingers 79 and 83, which are bridged by contact segment 82 of the sequence drum 45 and interloc'k 10-out. i Y

Upon the closure of the switchesl and 15. a circuit is established from the end tap of the secondary winding 27 of the main transformer 28 through the primary Wind'- ing 74 of the current transformer 75, primary winding 17 of the phase-converter 16, switch 15, a portion of preventive coil 84, and switch 1 to the secondary winding 27 of the main transformer 28. The energization of the primary winding 17 of the phaseconverter 16. which is effected by the closure of switches 1 and 15, tends to prevent overspeeding of the phase-converter 16 by the starting motor 33. v I

\V hen the phase converter 16 attains substantially synchronous speed, the phase-converter relay 47a closes, thereby effecting the energization of the auxiliary phase-converter relay 85. The energization of the actuating coil of the auxiliary phase-converter relay 85 effects the opening of relay 85 and switch 14. The relay 85 is maintained in its open position by means of a holding circuit from the battery 73 through manually-operated switch 72, actuating coil of the auxiliary phase-converter relay 85 and the contact members thereof to the negative terminal of the battery 73. The switch 14 will remain in its open position until the manually-operated switch 72 has been actuated to its open position and again closed.

The purpose of the relay 85 is to prevent improper starting of the phase-converter 16, once the phase-converter has been rendered inoperative by reason of its being disconnected for too long an interval from the trolley conductor 21, or for any other reason.

lVhen the switch 14 assumes its open position. the auxiliary or starting motor 33 is disconnected from the primary winding 17 of the phase-converter 16, and the starting motor 33 no longer serves to drive the rotor of the phase-converter 19. Upon the openingof the switch 14, a circuit is established from the battery 73,, through manuallyoperable switch 72, interlocks 10-out, 14-out pad and lfi-in and parallehconnected actuating;

00115.62, and 69fowthe.. BK engine 46 to the negative terminal of; the battery 73.

\Vhen thecoilS'162;.-and, 69 of the PK'engineAG are-energized, the-sequence drum 45 r oft; position, 'segment..82. will nolongen engagev the-controhfingers 79, 81, and 83; of the; sequen er drum 45, anduthe ?energization of the switches 1 and will be irendered independent otthe startingmotor relay 46a. Switches. to, 7;. inclusive 13: and 10 will e cl sed ,in th r; prade vm.ined-.. qu pon. th eque ce. i lll 14:5 occ pying; P tionsbgtoi,inclu$ive. v

V If, upon. the closure 'of any one ofthe switches 2. Qi :7, inclusio '..13,. the' current traversing the; .primary.,,winding; 17. of the phasc ccn verter 1Q exceedsapredetermined value, tll$fl0t1l3bll1i00lll0f the current-limit relay. 48mwill be-energized sul'liciently to effect the opening of the relay 48a; \Vhen the current limit relay 48a assumesits open position, the actuating coil.:4:9=of the-off val-vefi5v of the BK engine4l6=will be decnergized, thus bringingthesequence drum to ,rest,. as previously explained;

than. the current traversing the primary winding;17 of-. thaphase-converter 16 falls below this predetermined value, the relay deviceASmwVill assume its closed position, thereby i'eeenergizing. the coil 69 of the oil? valve andthus permitting further actuationof thedrum 451by the piston 51.

Closure of the switches 2 to 7, inclusive, and 13, as illustrated by Fig. 2 of the se quence chart, effects a gradual increase in the energization of the primary winding 17 of the phase-converter 16.

When the switch 10 is closed, upon the energization of its actuating coil through the contact segment 86 of the sequence drum 45, in'position'z' thereof, both coils 62 and 69 of the on and off valves 56 and 55. respectively, of the PK engine are de-energized by the interlock lO-out. The PK engine 46 will then return the sequence drum 45 to its off position. The switch 10 is maintained in its closed position by a holding circuit from the positive terminal of the battery 73 through manually-operable switch 72, interlock 10-in and the actuating coil of the switch 10 to the negative terminal of the battery 73.

When the sequence drum 45 occupies its 03 position, control of the switches 1 to 15, inclusive, with the exception of switches queuce drum 45. when. thesequence drum 45' occupiesits off posit-ion. 1

Ait'ter the closure: of the switch 10, the changeover switch -43 is automatically actu ated from its stanting position to its running position. The movement of the changeover switch 48*. may be gOVernedl' by suitable interlocking: with the switch 10., which it has not: been considered: necessary to illustrate. a k a From the above: descn'iption, it s is apparent that apparatus constructed in. accordance with my invention. will effect a gradual encrgization of theprimary windingv 17v of the phasaconver-ter 16, without. the addition of any main switches, onlytheiswitch 15 being re-positioned; and! thatthe operation of these switches is governedby a sequence drum and a current-limitrelay, which are the only I additional apparatus required.

While I' h'aaieshown my invention in. its preferred form, it ismpparentthat modifi: ations may be mad'e in' the-apparatus and arrangement of circuits without departing from the spirit of my invention. 'I desire, therefore, tolbe limited only by the scope of the appendedi claims.

- I claim asiny invention 1. In a motor-control system, the combination with a transformer and a phase-converter having a. primary and a secondary winding, of means comprising: a plurality of switches for =connecting said-pnima-ry and secondary windings to said transformer, and means comprising said switches and: a current-limit relay for gradually. and automatically increasing the voltage impressed upon saidprimary winding during the starting period of said phase-converter.

2. In aimotor-control system, the combination. with a. transformer and. a phasecouverter havinga; primary and a secondary winding, of; means comprising a plurality of switches forconnecting said prinniry and secondary windings to said transformer. and means comprising asequenoe drum and a current-limit relay. for. effecting the operation of said switches-to.gradually energize said primary windingduring the starting period of said phase-converter.

3. In a motor-tontrol system. the combination with a transihnner-and a phase-converter having a primaryand a secondary winding, of means comprising a plurality of switches for gradually energizing said primary winding during the starting period of said phase-converter, means comprising said switches for varying the connections of said primary and secondary windings to effect phase-balancing, and means for rendering said second means operative only after said first? means has operated.

4. In a motor-control system, the combination with a transformer and a phaseconverter having a primary and a secondary winding, of a plurality of switches for connecting said primary and said secondary windings to said transformer, means comprising a motor for starting said phaseconverter, means for closing said switches in a predetermined sequence to gradually energize said primary winding during the starting of said phase-converter, means for rendering said closing means inoperative, and means for governing said switches to maintain the currents traversing said primary and secondary windings in predetermined relation.

5. In a motor-control system, the combination with a transformer having a plurality of taps, and a phase-converter having a primary and a secondary winding, of means comprising a plurality of switches for connecting said primary and secondary winding to said taps, a switch for directly connecting said primary and said secondary winding, a motor for starting said phase-converter, a switch for energizing said motor, a sequence drum for governing said switches to effect gradual energization of said primary winding, means for controlling said sequence drum, and means for governing said switches independently of said controlling means to effect phase-balancing of the outgoing phases of said phase-converter 6. In a motor-control system, the co1n bination with a transformer and a phaseconverter having a primary and a secondary winding, of means for effecting phasebalancing of the outgoing phases of said windin s, means for gradually energizing said windings during the starting of said phase-converter, and means for rendering said phase-balancing means inoperative until after said phase-converter has been brought to a predetermined speed.

7. In a motor-control system, the combination with a transformer and a phaseconverter having a primary and a secondary winding, of means comprising a plurality of groups of switches for connecting said windings to said transformer, a switch for connecting said groups of switches together only during the starting of said phase-converter, and means for governing said switches during the starting of said phaseconverter and during its normal operation.

8. In a motor-control system, the combination with a transformer and a phaseconverter having a primary and a secondary winding, of means comprising a group of switches for connecting said primary winding to one portion of said transformer, means comprising another group of switches for connecting said secondary winding .to said transformer and means for interconnecting said groups of switches during the starting of said phase-converter for gradu ally energizing the primary winding of sa i d phase-converter.

9. In a motor-control system, the combination with a transformer and a phaseconverter having a primary and a secondary winding, of means comprising a group of switches for connecting said primary winding of one portion of said transformer. means comprising a second oup of switches for connecting said secon ary winding to said transformer, a switch for connecting said second group of switches to said primary winding during the starting of said phaseconverter, means comprising a sequence drum for governing the operation of said switches during the starting of said phase-converter, means comprising a relay device for governing the movement of said sequence drum in accordance with the energization of said phase-converter, and means for governing the operation of said switches independently of said drum, provided the drum occupies a predetermined position.

10. In a motor-control system, the combination with a transformer having a plurality of taps and a phase-converter having a primary and a secondary winding, of

.means comprising a group of switches for connecting said primary winding to certain of said taps, means comprising asecond group of switches for connecting said secondary winding to others of said taps, a switch for connecting said second group of switches to said primary winding, a motor for starting said phase-converter, a switch for connecting said motor in series relation with said primary winding, means comprising a sequence drum having a plurality of positions and a current-limit relay for governing the closure of said switches to start said phase-converter, means for returning said drum to a predetermined position after said phase-converter has attained a predetermined speed, and means for independently governing certain of said switches upon said drum returning to a predetermined position.

11. In a motor-control system, the combination with a transformer having a plurality of taps, and a phase-converter having a primary and a secondary winding, of means comprising a plurality of switches for connecting said primary and secondary winding to said taps, a switch for directly connecting said primalfi and said secondary kill wii-fding, ainotor f0r"st:1rtingsaid phaseswitches independently (if said automatic converter, 4 switch for energizing said means to effect phase-balancing of the Out- 10 1110tG1',"-a sequence drum for governing said goingphases of saidpha'se-converter.

switches to eiTe'c-t gradual 'energization of In testimony whereof, I have hereunto I said primary winding,mea.ns responsive to subscribed my name this 14th day of theicurrent traversing the primary winding December 1921. for automatically governing said sequence drum, and means for governing said JAMES R. \VILSON. 

